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The Benefits of Energy Crop Cultivation Outweigh the Costs
21 May 2010
An article in the current issue of Global Change Biology Bioenergy reveals that Miscanthus x giganteus, a perennial grass, could effectively reduce our dependence on fossil fuels, while lowering atmospheric CO2.
Using a simulation tool that models the future global climate, researchers predict that the carbon that is released into the atmosphere from the loss of natural vegetation will be paid back by Miscanthus within 30 years.. Previous estimates for other liquid biofuels, such as corn ethanol, were estimated to take 167-420 years to pay back their carbon debt.
The global concern over climate change has challenged researchers to explore ways to mitigate the damage we are doing to our environment. They are looking more closely at energy crops, like Miscanthus, to replace our need for fossil fuels like natural gas and oil, which raise atmospheric CO2 concentrations.
According to John Hughes, UK Met Office Research Scientist, "Our study demonstrates the huge potential of energy crops, in particular of Miscanthus. Also, by scaling the results up to the global scale as we do in this study we are developing a new set of tools for evaluating energy crops."
A process-based model of the energy crop Miscanthus×giganteus is integrated into the global climate impact model IMOGEN, simulating the potential of large-scale Miscanthus plantation to offset fossil fuel emissions during the 21st century. This simulation produces spatially explicit, annual projections of Miscanthus yields from the present day to the year 2100 under an SRES A2 anthropogenic emissions scenario and includes the effects of climate change. IMOGEN also simulates natural vegetation and soil carbon storage throughout the 21st century. The benefit of Miscanthus cultivation (avoiding fossil fuel emissions of CO2) is then compared with the cost of displacing natural vegetation (carbon emissions from vegetation and soil). The time taken for these effects to cancel out, the pay-back time, is calculated regionally. The effects of large-scale Miscanthus plantation are then integrated globally to produce an estimate of atmospheric CO2 concentrations throughout the 21st century. Our best estimate of the pay-back time for Miscanthus plantation is 30 years. We project a maximum possible reduction in atmospheric CO2 of 323 ppmv by the end of 21st century, with a reduction of 162 ppmv corresponding to the best estimate scenario.